Warschau, Polen  /  17.9.2018  -  20.9.2018

E-MRS Fall Meeting 2018

Zwei Mal pro Jahr treffen sich Experten aus Industrie, Wissenschaft und Forschung, um im Rahmen der Tagungen der European Materials Research Society E-MRS aktuelle technologische Entwicklungen im Bereich der Materialforschung zu diskutieren.

In einem Vortrag stellt Hunter King, Doktorand in der Gruppe »Heißdrath-CVD« am Fraunhofer-Institut für Schicht- und Oberflächentechnik  IST während des E-MRS Fall Meetings innerhalb des Symposiums »Monolithic and heterogeneous integration of advanced materials & devices on silicon« seine Forschungsergebnisse zum Einfluß des Dotierniveaus auf den Anteil der Kristallinität bei der Herstellung von nanokristallinen Siliziumschichten (nc:-Si:H) mittles Heißdraht-CVD vor.

 

Mittwoch, 19. September 2018

16:45 Uhr

»Effect of doping level on crystallite fraction of as-grown nc-Si:H by hot-wire chemical vapor deposition (HWCVD)«

Hunter King

The crystallite fraction of nano-crystalline Si:H (nc-Si:H) films deposited by means of hot-wire chemical vapor deposition (HWCVD) is investigated. The effect of Phosphorus and Boron as dopants on the film structure with varying levels of additional in-situ H2 gas are compared to un-doped control runs. All films were produced in a large scale inline coater using an array of 10 0.5 mm Tungsten wires with 50 mm spacing, kept at 2100 °C, with a filament to substrate spacing of 75 mm. The level of dopant gas flow relative to the Silane (SiH4) process gas flow was varied from 0.1 % to 1.0 % for n-doping (PH3), and from 0.01 % to 0.67 % for p-doping (B2H6). The crystallinity in the films was investigated via Raman spectroscopy, X-ray diffraction (XRD) and SEM imaging. The dopant concentration is found to have a strong effect on the hydrogen gas flow required for film crystallization. The increase of n-type doping corresponded to a shift of the onset of crystallinity by 500 sccm of H2 flow. Whereas the increase in p-type doping shifted the onset of crystallinity in the films, such that no crystallinity was measured in the 0.67 % B2H6 films within the working range of the device (5050 sccm H2 maximum flow). The final reachable value of crystallinity in the Silicon films also shows a strong dependency on the type and the level of doping. With an increase of doping corresponding to a strong decrease in maximum reachable crystallite fraction. The different behavior of P and B dopants may be explained by a size effect (misfit of covalent radii) or by a chemical effect.